ANOTHER NIGHTMARE: A policeman secures the scene where a fellow cop was blown away yesterday on campus at Virginia Tech. Photo: AP

ANOTHER NIGHTMARE:A policeman secures the scene where a fellow cop was blown away yesterday on campus at Virginia Tech (AP)

In a haunting replay of carnage on a campus where one of America’s worst mass murders unfolded in 2007, a Virginia Tech cop was shot to death yesterday by a killer who then turned the gun on himself.

“Our hearts are broken again,” university President Charles Steger said after lifting a four-hour lockdown on the tragedy-wracked campus.

The “wanton violence” occurred at 12:15 p.m. as Army veteran and father of five Deriek Crouse, 39, questioned a driver he had pulled over at a parking lot on campus.

Suddenly, a gunman strode up to Crouse and blew him away, then bolted for a lot where a body was found minutes later with a self-inflicted gunshot wound, Fox News reported. A gun was recovered nearby.

Fox reported the gunman was believed to be a Virginia Tech student.

“I think investigators feel confident they’ve found the [the shooter],” state police Sgt. Bob Carpentieri said, refusing to directly confirm that the dead man was the assassin. “You can kind of read between the lines.”

Carpentieri said the gunman was not the driver the officer had stopped — and it’s not clear if Crouse, who worked at a jail and a sheriff’s department before becoming a campus cop in 2007, was specifically targeted.

He said, however, that investigators were looking into whether the shooter was linked to an armed robbery earlier in the day in Radford, Va., not far from the Blacksburg campus.

Authorities hadn’t identified the suspected shooter by last night.

The attack occurred as an estimated 18,000 students and teachers prepared for final exams. No classes were in session.

The shooting came soon after the conclusion of a hearing where Virginia Tech was appealing a $55,000 fine by the federal Education Department in connection with the university’s response to the rampage on April 16, 2007.

The department said the school violated the law by waiting more than two hours after two students were shot to death in their dorm before sending an e-mail warning. Virginia Tech student Seung-Hui Cho ulitimately killed 32 people, and then himself.

The latest shooting “just brings up a lot of bad feelings, bad memories,” said Derek O’Dell, a veterinary student who was wounded in the 2007 shootings.

“You pray there are no more victims, and pray for the families.”

O’Dell was monitoring the situation from his home a couple of miles from campus.

Corey Smith, a 19-year-old sophomore, said, “It’s crazy that someone would go and do something like that, with all the stuff that happened in 2007.”

Partially as a result of the 2007 shooting, a massive digital-alert system — including e-mails and texts — was activated as soon as authorities learned of the shooting.

“We deployed them all, and we deployed them immediately to get the word out,” said school spokesman Mark Owczarski.

It’s not the first time the school has used the alert system.

In August, a report of a possible gunman set off the longest, most extensive lockdown and search on campus since 2007. No gunman was found, and the school gave the all-clear about five hours later.